Smart phones and similar display-based devices typically have a touch sensor integrated with the display or the display cover of the device. The touch sensor provides touch-sensing functionality by sensing the position (and in some cases the movement) of a user's touch and uses this information to carry out one or more device functions.
It is also desirable for display-based devices to have additional functionality beyond mere touch-location sensing. Other functionalities include a pressure sensing, acoustic sensing, acceleration sensing and vibrational energy harvesting. It may also be desirable for the display-based device to have multiple touch-sensing functionalities.
Besides touch-sensing features, the covers for display-based devices need to be durable, i.e., scratch-resistant and break-resistant, while also having strong optical performance characteristics (e.g., high optical transmission, low reflectivity, low distortion, good color, etc.).